The unified_resources.db grew without bound (2GB reported) because:
1. No VACUUM: DELETE freed rows internally but never shrank the file.
Added auto_vacuum(INCREMENTAL) to the DSN for new databases, plus a
one-time migrateAutoVacuum() that converts existing databases.
reclaimFreePages() now runs after each prune cycle to return freed
pages to the OS via PRAGMA incremental_vacuum.
2. Missing retention: action_lifecycle_events, export_audits, and
loop_reports had no retention at all. Added 90-day retention for
lifecycle/export audits and 30-day for loop_reports, matching the
existing action_audits/resource_changes cadence.
3. Slow cleanup cadence: the retention loop ran every 6h and never on
startup. Reduced to hourly and added an initial prune 30s after
startup so a restart with a bloated DB starts recovering immediately.
Mirrors the proven pattern from metrics.db (auto_vacuum INCREMENTAL +
incremental_vacuum + WAL checkpoint).
Refs #1496
028e8c8df2